This invention relates to a compressor for use in an automobile air conditioner and, in particular, to an improvement of a bearing structure supporting an end of a shaft.
As a typical compressor of the type, there is known a swash-plate compressor having a structure illustrated in FIG. 1. The swash-plate compressor comprises a front housing 1, a cylinder block 2xe2x80x2, and a rear housing (cylinder head) 3 assembled together by the use of a through bolt 4 penetrating through the front housing 1 and the cylinder block 2xe2x80x2 to be received in the rear housing 3. Specifically, the front housing 1 is coupled to a front end of the cylinder block 2xe2x80x2 while the rear housing 3 is coupled to a rear end of the cylinder block 2xe2x80x2 with a valve plate 9 interposed therebetween. A combination of the front housing 1 and the cylinder block 2xe2x80x2 defines a crank chamber 15 in which a shaft (drive shaft) 5xe2x80x2 extends in an axial direction. The shaft 5xe2x80x2 is rotatably supported by a pair of bearings 18 and 19 attached to the cylinder block 2xe2x80x2 and the front housing 1, respectively. Upon assembling, the shaft 5xe2x80x2 is inserted through the front housing 1 towards the rear housing 3 until one end of the shaft 5xe2x80x2 is received in a receptacle portion of the cylinder block 2xe2x80x2. At this time, the one end of the shaft 5xe2x80x2 is pushed back by an adjusting screw 22 disposed in the cylinder block 2xe2x80x2 towards the front housing 1 to leave an axial clearance. Thus, the adjusting screw 22 serves to adjust the axial clearance of the shaft 5xe2x80x2. The cylinder block 2xe2x80x2 is provided with a plurality of cylinder bores 8 formed at positions surrounding the shaft 5xe2x80x2 to receive a plurality of pistons 7 inserted therein, respectively.
Within the crank chamber 15, a swash plate 6 to coupled to the shaft 5xe2x80x2. Specifically, the shaft 5xe2x80x2 is inserted into a through hole formed in the swash plate 6 to fix the swash plate 6 around the shaft 5xe2x80x2. Between the swash plate 6 and the front housing 1, a thrust bearing 20 having elasticity is interposed to urge the swash plate 6 towards the rear housing 3. The swash plate 6 has an outer peripheral portion kept in contact with a plurality of semispherical shoes 23 as a coupling mechanism. Each of the shoes 23 has an outer semispherical surface engaged with a ball bearing surface of each of the pistons 7. Following the rotation of the shaft 5xe2x80x2, each of the pistons 7 coupled through the shoe 23 to the swash plate 6 performs reciprocal movement within the cylinder bore 8.
The rear housing 3 has an inner space divided into a suction chamber 10 and a discharge chamber 11. The valve plate 9 is provided with a suction port 12 and a discharge port 13 formed in an area corresponding to each cylinder bore 8. A compression space is formed between the valve plate 9 and each of the pistons 7. Through the suction port 12 and the discharge port 13, the compression space communicates with the suction chamber 10 and the discharge chamber 11, respectively. Each suction port 12 is provided with a valve (not shown) for opening and closing the suction port 12 in response to the reciprocal movement of the piston 7. Likewise, each discharge port 13 is provided with a valve (not shown) for opening and closing the discharge port 13 under the restraint of a retainer 14 in response to the reciprocal movement of the piston 7.
The swash-plate compressor described above is of a fixed displacement type. When the swash plate 6 is rotated following the rotation of the shaft 5xe2x80x2, the rotation is transmitted through the shoe 23 to each piston 7 so that each piston 7 performs the reciprocal movement within the cylinder bore 8. As a consequence, a refrigerant gas is sucked from the suction chamber 10 through the suction port 12 into the compression chamber. The refrigerant gas is compressed within the compression chamber and then discharged through the discharge port 13 to the discharge chamber 11.
In the swash-plate compressor described above, the adjusting screw for adjusting the axial clearance of the shaft is used. The use of such adjusting screw is disclosed in Japanese Utility Model Publication (JP-Y) No. 3-41101 (41101/1991) which is directed to a variable-displacement compressor.
In the swash-plate compressor described above, the front housing, the cylinder block, and the rear housing are fixed by the use of the through bolt. Alternatively, the front housing and the cylinder block are fixed by a first through bolt while the cylinder block and the rear housing are fixed by a second through bolt. In either event, an assembling process is carried out in the following manner. At first, the shaft, the swash plate, and the piston are coupled to the front housing and the cylinder block. In order to adjust the axial clearance of the shaft, the front housing and the cylinder block are temporarily assembled with the above-mentioned components coupled thereto. An axial end surface at the one end of the shaft is pressed by the adjusting screw to adjust the axial clearance. Thereafter, in order to prevent the adjusting screw from being loosened, an anti-loosening procedure is taken, for example, a head of the adjusting screw is collapsed or caulked. After the other components including the valve plate and the rear housing are coupled, final or permanent assembling is carried out. Thus, the assembling process requires two separate stages including the temporary assembling and the final assembling between which the adjustment of axial clearance and the anti-loosening procedure are carried out. Thus, the assembling process is complicated, time-consuming, and inefficient.
It is an object of the present invention to provide a compressor which is capable of easily adjusting an axial clearance of a shaft and which can be assembled by a simple process with excellent efficiency.
Other objects of the present invention will become clear as the description proceeds.
According to an aspect of the present invention, there is provided a compressor which comprises a cylinder block, a front housing coupled to the cylinder block, a shaft extended in an axial direction and rotatably supported by the cylinder block and the front housing, the shaft being rotated to cause a compressing operation of the compressor, an axial urging arrangement having a compression coil spring for urging the shaft in the axial direction, and a thrust bearing, the axial urging arrangement and the thrust bearing being arranged in series and interposed between an axial end surface of the shaft and the cylinder block.
According to another aspect of the present invention, there is provided a compressor which comprises a cylinder block having a receptacle portion, a shaft extending in an axial direction and having one end inserted into the receptacle portion, a collar fitted over the one end of the shaft, the collar being unrotatable and axially movable with respect to the shaft, and an elastic member arranged inside to elastically urge an axial end surface of the shaft.
According to still another aspect of the present invention, there is provided a compressor which comprises a cylinder block having a plurality of cylinders, a plurality of single-headed pistons adapted to perform reciprocal movement within the cylinders, respectively, a front housing coupled to the cylinder block, a shaft supported by the cylinder block and the front housing, a swash plate integrally fixed to the shaft, a plurality of shoes each of which is interposed between the swash plate and each of the pistons, a pair of radial bearings arranged in the front housing and the cylinder block, respectively, to radially support the shaft, a thrust race bearing arranged between the front housing and the swash plate, a spring for urging an axial end surface of the shaft towards the front housing, and an interposed member interposed between the spring and the axial end surface of the shaft, the cylinder block having a stepped portion which serves to receive the spring abutted thereto so that the shaft is axially supported.